The present invention relates to obstacle detection devices to be used by visually impaired pedestrians. More particularly, the present invention relates to an ultrasonic-based obstacle detection device.
The task facing visually impaired pedestrians is the task of independently starting from a point and ending at a destination. This seems simple. However, it appears to be extremely challenging once the factors affecting mobility are taken into account. If one were to close his eyes and tried to move just a few steps, it would not take long for him to realize that the visually impaired have no access to basic information such as spatial orientation, the nature of the obstacles, the presence of moving objects, or even the boundaries of the path or travel surface.
Travelling aids have long been developed in efforts to allow visually impaired pedestrians to travel and move about safely and comfortably. One of the first versions and the most widely used up to the present is the long cane. Since the 1960""s, several types of electronic travel aids (ETA) have been developed to improve the mobility of visually impaired pedestrians. Some of these devices are now currently available. The Russell Pathfinder provides one such example. It first came into use in 1965 and employs an ultrasonic beam to detect objects. It provides a vibrating warning that is inversely proportional to the distance. The Nottingham Obstacle Detector, designed in 1973, is a hand-held device that provides an auditory readout of the distance between the visually impaired individual and the object with eight musical notes. Recent technical development permits the use of a human voice to communicate the distance between the visually impaired individual and the object by a voice message.
U.S. Pat. No. 4,870,687 to Deleon discloses an oral readout rangefinder. It orally announces the measured distance by using of a speech synthesiser. U.S. Pat. No. 5,508,699 to Silverman discloses a dual sensing identifier/locator device for the visually impaired. It composes of two parts. Transmitters attached to a variety of objects send out coded signals to indicate the names of the objects. A receiver attached to the user decodes the signal and produces audible output that includes the name of the object and the distance. U.S. Pat. No. 5,347,273 to Katiraie discloses an ultrasonic detection system. It is basically a collision sensing system used by both automobiles and the visually impaired. For the visually impaired application, transducers are mounted on a cane. It gives the exact distance of an obstacle from the visually impaired using the device by a voice message. U.S. Pat. No. 5,724,313 to Burgess et al discloses a guide device using pitches and tones to inform the user of the nature of the obstacle.
All of these devices, some of which have been innovative in their own way, have serious deficiencies. They have often lacked functionality and compactness necessary for one who will use the device while walking. The distance information provided has often at best been impractical and at worst incomprehensible to a visually impaired individual. They generally have lacked the ability to adapt to the needs and characteristics of the visually impaired individual who will use the device. Thus, what is needed is a compact, functional device that readily adapts to the needs and characteristics of a visually impaired individual. A device which provides in a readily comprehensible and intuitive form information on the distance between a visually impaired individual and an object that person is approaching.
It is an object of the present invention to provide an ETA method and apparatus for a visually impaired individual that is economical and easy to use so that a visually impaired individual can safely move about on his or her own.
It is an object of the present invention to provide an ETA obstacle detection device and method for guiding visually impaired pedestrians in a safe, comfortable and easy manner.
It is yet another object of the present invention to provide an ETA method and apparatus which provides information on distance to an object in an intuitive manner which makes it easy for the visually impaired individual to easily and quickly understand the distance units and what they actually represent in their own experience.
It is yet another object of the present invention to provide an ETA with a method and apparatus which provides distance information in units of step or stride of an individual.
It is yet another object of the present invention to provide a means for the user to calibrate the apparatus to their own personal preferences or characteristics.
It is yet another object of the present invention to provide an ETA apparatus which is provided in an easy to use, compact and unobtrusive package.
The present invention provides an ETA apparatus and system which uses ultrasonic sound as a ranging medium with a dual channel transducer driver system to determine by echo ranging the distance of objects in front of a user of the ETA apparatus. The apparatus converts the information obtained from the time difference between an ultrasonic transmission and its subsequent echo to determine distance and it communicates the measure of distance to the user in measurements of normal human strides. The information on distance is presented to the user by pre-recorded statements of the number of strides or steps to the object or obstacle detected.
In a further aspect of the present invention, a twin channel transducer allows it to discriminate between objects that are on the left or right side of the path of travel of the user and to determine which is closer.
In yet another aspect of the invention information on distances and location of objects is provided to the user by a dual channel sound system that discriminates between objects or obstacles on the left or right of the user. The system, in its preferred embodiment, has ear phones for each ear which transmit the information by the left or right or both audio channels depending on the position of an obstacle or obstacles by sending an audio signal that is louder to the side that the an object is closer on as well as an audio distance message.
In yet another aspect of the present invention it incorporates the ETA of the present invention within the frame of glasses for the visually impaired pedestrian. The electronics is in a miniaturized configuration.
In yet further aspect of the present invention it provides a method and apparatus for the user to calibrate the distance of the stride used to measure and inform the user of distance to an object to the users preferred stride or step characteristics.